In many applications, it is desirable to record substantially identical photographic film and electronic video images of a subject. The recorded video images can then be used, for example, as electronic "proofs" of the picture composition before the expense of developing and printing the photographic negatives is incurred. As is well known to those skilled in the art, flash illumination is required for most indoor, and some outdoor, photographic opportunities. During such a flash exposure, the film camera lens remains open for a predetermined period of time, while the flash illumination is provided during a window of time within this predetermined period. Because the flash illumination substantially entirely defines the exposure onto the photographic film, and because the flash illumination time is short, the operation of the film and video cameras must be carefully synchronized to obtain substantially identical images. This synchronization is not believed to be satisfactorily provided by currently known imaging systems.
European Patent Application No. 0 196 009 shows a still camera wherein a photosensitive film and a solid state imaging element are positioned in a single camera body to record substantially identical views of a subject. Apparatus is provided for viewing the stored video images, for example to preview the film images, on a small, attached display. This patent suffers from the disadvantage, however, that while a conventional electronic flash "shoe" attachment is shown, no suggestion is made as to how the film exposure and video recording are synchronized to a flash illumination.
U.S. Pat. No. 4,635,123 to Masunaga et al. shows an electronic imaging system incorporating a solid state image pick-up device, including a photoelectric conversion portion and a memory portion, operating in synchronization with a flash. The system operates to record a full frame video image of a subject subsequent to the triggering of the flash. The patent shows several methods of synchronizing the flash with the pick-up device such that flash illumination is inhibited during the transfer of charge from the photoelectric conversion portion to the memory portion. The patent further shows several electronic imaging systems wherein the illumination provided is based on the accumulation of charge within the image device, so as to obtain a proper exposure of the pick-up device.
The Masunaga et al. patent does not show or suggest the synchronization of the electronic imaging system with a photographic film camera. Further, the synchronization of the flash to the video components of the imaging system inherently produces undesirable results in the recording of the video image. More specifically, because the flash illumination is delayed during the transfer of charge within the pick-up device, a time period of up to 1/60 of a second, the image recorded will not be exactly what the operator intended to record. This period of time may be sufficient, for example, for a human subject to blink and alter the intended image.
U.S. Pat. No. 4,366,501 to Tsunekawa et al. shows a video image recording system synchronized to operate with an electronic flash so as to record a full frame video image of a subject pursuant to the actuation of a release and the triggering of the flash. In a first mode of operation a solid state imager accumulates untransferred dark current between picture recordings. Upon activation of the release, a frame of charge is transferred from the imager to "clear" it in preparation for recording. The flash is then triggered, and the next two consecutive fields of video information are recorded in a frame store. In a second mode of operation, the imager is operated in a "movie" mode, that is, it is read periodically at an NTSC compatible data rate. When the flash is used, the release is actuated, and the triggering of the flash is delayed to coincide with the completion of a charge transfer within the imager.
The Tsunekawa et al. patent does not show or suggest any synchronizing of the video image recording system with a film camera. Further, similarly to the Masunaga et al. patent discussed above, the operation of the flash is synchronized to the operation of the video camera. This necessitates the above described delay of at least one video field (i.e. 1/60th of a second), and possibly one frame (1/30th of a second), between the activation of the release button and the triggering of the flash to illuminate the subject. As described above, such delays are inherently undesirable in the operation of imaging systems.
Systems are known in which separate photographic film and video cameras are arranged to synchronously record a substantially identical subject image during a single illumination of an electronic flash. These systems, one example of which is the Noritsu model VSS-2, are typically NTSC compatible, with the recorded video image being displayable on a conventional NTSC video display. These systems suffer, however, from the disadvantage that only one half of the NTSC video frame (i.e. one field) is recorded in synchronization with the flash illumination. The resulting video images are substantially lacking in detail, especially when they are displayed on high resolution video monitors.